Life is a Garden | South Africa |

"Aquatic invasive alien plants pose significant environmental, economic and social problems," says Working for Water's, Debbie Sharp. An aquatic weeds expert, she was speaking at the start of National Weedbuster Week (October 5-11), which is this year themed, "My River, My Life".

WeedBuster Week highlights the continuous government campaign to contain the spread of invasive alien plants and invasive aquatic weeds. This 15-year-old project is a multi-departmental initiative led by the Department of Water and Environmental Affairs through the Working for Water (WfW) programme, and is supported by various partners and stakeholders.

As a homeowner, it is both illegal and environmental irresponsible to contribute to the problem by having declared aquatic IAPs on your property.
All it takes to start an infestation is an escaped bit of leaf or stem. Once they enter a water system they spread rapidly and can clog up a river within a season, affecting recreational use and unbalancing the local ecosystem.

What is happening with water weeds around the country?

Kwazulu-Natal

The discovery of hydrilla, in the Pongolapoort Dam, for example, was a major shock to KZN authorities - as there were strict laws in force to prevent the plant from entering the country. Within only a few years, this submerged perennial aquatic invader from the warmer regions of Asia, had taken over 800 hectares of water in the Pongolapoort Dam.

Working for Water aquatic squads are currently working to manually removed hydrilla from the dam. There is also a prevention campaign aimed at motor boats from moving tiny pieces of hydrilla to other dams in KZN where they may create havoc.

Hydrilla aside, the ‘big five' aquatic invaders in KwaZulu-Natal are still water hyacinth, red water fern, kariba weed, water lettuce and parrots feather. By far the biggest problem is water hyacinth which thrives in our climate where there are no cold winters to slow its growth. It is at its worst in the Msunduzi and Umgeni Rivers where its control, through aerial spraying and teams on the ground with backpacks, is costing millions of rand each year.

Western Cape

Over the past two years, parrot's feather and water hyacinth have been a problem in the upper reaches of the Breede River and the lower Berg River. Both areas required an expensive control and clearing operation with taxpayer funds.

This summer, make sure that the dams and water features in your areas don't harbour parrot's feather (Myriophyllum aquaticum), a South American floating aquatic plant with pale green, finely divided, feather-like leaves. It is also important to report pet shops that sell parrot's feather or other submerged aquatic weeds such as cabomba for fish tanks and aquariums (see Working for Water hotline below) as this is illegal.

Eastern Cape

In the Eastern Cape, water hyacinth and parrot's feather are by far the biggest problem. Researchers from Rhodes University are at the forefront of the challenge and have received international recognition for their work into the biocontrol of water hyacinth on New Year's Dam, Alicedale.

Gauteng

By far the biggest aquatic invader problem in Gauteng is the beautiful, but highly problematic water hyacinth (Eichhornia crassipes), a South American perennial that has invaded the Benoni Lakes system, Vaal River, Crocodile River and even Roodeplaat Dam, north-east of Pretoria.

In the Vaal River, large restraining chains erected near Orkney to stop plants drifting down the river can create kilometer-long dense mats of biomass 1-2m thick. Cold winters turn these mats brown and after herbicide spraying, they sink to the bottom of the river causing a huge chemical imbalance due to the rotting vegetation in the water.

In the case of the Benoni Lakes and Roodeplaat Dam, thick mats of water hyacinth have reduced light and oxygen in the water which makes it difficult for aquatic plants to survive. Animal life that is dependent on a diversity of plant life for survival, in turn, dies out. Fishermen are affected, irrigation intakes are clogged up, yachting, rowing and canoeing comes to a halt and tourism is at risk.

Mpumalanga

With water hyacinth spreading down the Crocodile, Letaba and Olifants Rivers, water hyacinth invasions pose a serious future threat to tourism, water sports and the leisure fishing industry in Mpumalanga. Particularly in places such as the Loskop Dam Nature Reserve, the river frontage at Nelspruit's National Botanical Gardens and water pans in Kruger National Park.

North West

Affected by problems in Gauteng, the highly problematic water hyacinth (Eichhornia crassipes) has invaded Roodeplaat Dam, north-east of Pretoria and is making its way down the Crocodile River. It is also present in Roodekopjes Dam near Brits where it poses a serious threat to the bass fishing leisure industry.

Limpopo

Also affected by problems upstream, water hyacinth is spreading down the Crocodile, Letaba and Olifants Rivers, clogging up irrigation intakes and placing agriculture at risk. As has been shown so clearly on the Vaal River, water hyacinth invasions also pose a serious future threat to tourism, water sports and the leisure fishing industry in Limpopo.

Free State

One of the biggest problems in the Free State is red water fern (Azolla filiculoides), a South American mat-forming floating aquatic plant with silvery-green foliage that turns reddish-brown or purple in winter. It invades still or slow-moving water in rivers, lakes and ponds and can completely dry out farm dams. Its ability to live in the Free State's subzero temperatures during winter makes it a huge local problem.

Further west, there is a huge problem with water hyacinth in Vaal River catchment through to the Bloemhof Dam and as far as south as the town of Douglas – the confluence of the Vaal and Orange Rivers. Over 120km of the Vaal River is now deemed to be in a water hyacinth control zone and the aim has always been to try to keep water hyacinth out of the Orange River. This notwithstanding, control is a very difficult job owing to the large willow trees the line the banks of the Vaal River shielding water hyacinth from aerial spraying programmes.

To highlight the issues, the National Weedbuster Week celebration will be taking place at Hoopstad, near the Bloemhof Dam on 5 October, 2009.

Northern Cape

At present, water hyacinth is a huge problem in the Vaal River and authorities are desperately trying to keep it from creating a similar problem in the Orange River, the Northern Cape's largest water source.

In an effort to draw attention to the challenge of invasive aquatics upstream at the Bloemhof Dam, the National WeedBuster Week celebrations will be held in Hoopstad on Monday October 5.

Are your water plants illegal?

If you are a gardener, it is important not to be tempted to bring these beautiful, but highly invasive alien aquatics into your garden from

If you have an attractive aquatic IAP, such as water lettuce, parrot's feather or water hyacinth in your water feature, pond or dam, now is the time to remove it. Do this by putting the plant into a sealed plastic bag, before disposing of it safely.

This Weedbuster Week, become familiar with the many aquatic invaders that must be removed from your property. They include: Water hyacinth (Eichhornia crassipes), water lettuce (Pistia stratiotes), Kariba weed (Salvinia molesta), red water fern (Azolla filiculoides), parrot's feather (Myriophyllum aquaticum), spiked water-milfoil (Myriophyllum spicatum), dense water weed (Egeria densa), Canadian water weed (Elodea candensis) and Mexican water lily (Nymphaea mexicana),.

For more information contact:

• Tracey Fared, Communications and Education Unit Manager
  Working for Water, Department of Water and Environmental Affairs
  Cell: 079 439 4387
• Working for Water Hotline: 0800 005376
• To identify invasive alien plants, visit: www.agis.agric.za